Currently, in Third Generation (3G) mobile communication system and Long Term Evolution (LTE) system, usually distributed base station architecture is adopted for the base stations, i.e., the whole base station includes two parts: BaseBand processing Unit (BBU) and Radio Remote Unit (RRU). The BBU is mainly used to achieve functions of baseband processing, main control, transmission, clock, etc., while the RRU is mainly used to achieve functions of conversion between digital baseband signal and RF (Radio Frequency) signal, etc., The interface between the BBU and the RRU is a fiber optic interface.
FIG. 1 is a schematic diagram of compositional structure of a typical BBU with a three-sector configuration in the prior art. As shown in FIG. 1, the BBU includes: a main control transmission clock board, a baseband processing board and a backplane. The main control transmission clock board may be abbreviated as “main control board”, which is mainly used for main control, transmission and clock functions. Usually, all the processes over the BBU control level are performed by the main control transmission clock board. Thus, the main control transmission clock board is a nerve center of the whole BBU, which not only controls the operations of single-boards, but also provides clock signals and transmission interfaces for the single-boards. The baseband processing board can be abbreviated as “baseband board”, which is mainly adapted to perform the layer 1 and the layer 2 processes. The backplane is a PCB (Printed Circuit Board) mounted at the back of the BBU frame, which is adapted to interconnect among individual single-boards. The signal transmission between the individual single-boards and the power supply for the individual single-boards are all achieved by backplane bus, thereby avoiding the cable tangles of interconnection among the individual single-boards. In this way, the whole system has a very high reliability and easy maintenance.
In practice, each baseband processing board and its corresponding RRU are jointly responsible for the related processes of one cell, and thus the failure of any one of the baseband processing boards may lead to the failure of the cell for which the baseband processing board is responsible until the whole cell is out of service. In this case, the users in the whole cell can not communicate normally.
To solve the above problems, in the prior art, a backup baseband processing board is additionally provided in the BBU. The backup baseband processing board is connected with all RRUs. FIG. 2 is a schematic diagram of an arrangement way of a backup baseband processing board in the prior art. Once any one of the baseband processing board fails, the failed baseband processing board is replaced by this backup baseband processing board.
However, there are some problems for the way described above in practice, i.e., due to the additionally provided backup baseband processing board, accordingly the number of fiber optic interfaces is required to be doubled, and thus the implementation costs are relatively high.